Optical device and method for manufacturing the same, and electronic apparatus

ABSTRACT

An optical device includes a substrate having a through hole formed therein, and an optical element mounted on the substrate with its optical section being placed to face the through hole, and a light transmissive member disposed at the through hole. Light transmissive under-fill material is provided between the substrate and the optical element and between the light transmissive member and the optical element.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional patent application of U.S. Ser. No.10/032,227 now U.S. Pat. No. 6,765,236 filed Dec. 21, 2001, claimingpriority to Japanese Patent Application No. 2000-395112(P) filed Dec.26, 2000, all of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Technical Field of the Invention

The present invention relates to optical devices and methods formanufacturing the same, and electronic apparatuses using the same.

2. Prior Art

An optical device in which an optical element such as a solid imagingelement is sealed therein is known. The optical element is mounted on acircuit substrate, and a light receiving section or a light emittingsection of the optical element is disposed to face a through hole thatis formed in the circuit substrate. Also, a cover glass is adhered tothe circuit substrate in a manner to cover the through hole. Inaccordance with the conventional optical device, since a cover glass isadhered to the circuit substrate as described above, this causes aproblem in which its thickness becomes large. Furthermore, when a lensis mounted in addition to the cover glass, the thickness of the opticaldevice becomes much greater.

It is an object of the present invention to solve the problems describedabove, and to provide a thinner optical device and a method formanufacturing the same, and an electronic apparatus including the same.

SUMMARY OF THE INVENTION

An optical device in accordance with the present invention comprises asubstrate in which a through hole is formed; an optical element mountedon the substrate and having an optical section being placed to face thethrough hole; and a light transmissive member disposed at the throughhole. Since the light transmissive member is disposed at the throughhole, the optical device can be made thinner, smaller and lighter.

In the optical device, light transmissive under-fill material may beprovided between the substrate and the optical element and between thelight transmissive member and the optical element. As a result, theunder-fill material can prevent water penetration in optical sections.

In the optical device, a spacer may be interposed between the opticalelement and the light transmissive member. As a result, the lighttransmissive member is prevented from contacting the optical element,and position adjustment of the light transmissive member is possible.

In the optical device, the light transmissive member may be in the shapeof a lens. As a result, the light transmissive member itself serves as alens, and therefore the lens function can be added without increasingthe thickness.

An optical device in accordance with the present invention comprises asubstrate in which a through hole is formed; an optical element mountedon the substrate and having an optical section being placed to face thethrough hole; and a lens that is provided on the substrate and coversthe through hole. Since the lens covers the through hole, a cover glassis not required, and the optical device can be made thinner, smaller andlighter.

In the optical device, light transmissive under-fill material may beprovided between the substrate and the optical element and between thelens and the optical element. As a result, the under-fill materialprevents water penetration into optical sections.

In the optical device, a spacer may be interposed between the substrateand the lens. As a result, the position of the lens can be adjustedaccording to a focal distance of the lens.

In the optical device, an electronic element other than the opticalelement may be mounted on the substrate.

An electronic apparatus in accordance with the present inventioncomprises the optical device described above.

A method for manufacturing an optical device in accordance with thepresent invention comprises the steps of mounting an optical element ona substrate in which a through hole is formed in a manner that anoptical section thereof is placed to face the through hole; providinglight transmissive under-fill material between the substrate and theoptical element; and disposing a light transmissive member at thethrough hole.

Since the light transmissive member is disposed at the through hole, theoptical device can be made thinner, smaller and lighter.

In the method for manufacturing an optical device, a space between theoptical element and the light transmissive member may be regulated by aspacer. As a result, the light transmissive member is prevented fromcontacting the optical element, and positioning of the lighttransmissive member is possible.

In the method for manufacturing an optical device, the lighttransmissive member may be disposed at the through hole after theunder-fill material is provided. As a result, since the under-fillmaterial is provided in a state in which the through hole is opened, aircan be removed, and generation of bubbles can be prevented.

In the method for manufacturing an optical device, the under-fillmaterial may be provided after the light transmissive member is disposedat the through hole. As a result, the under-fill material can beprevented from flowing out from the through hole.

In the method for manufacturing an optical device, the lighttransmissive member may be disposed at the through hole after theoptical element is mounted on the substrate. As a result, the lighttransmissive member can be left intact without being influenced when anoptical element is mounted.

In the method for manufacturing an optical device, the optical elementmay be mounted on the substrate after the light transmissive member isdisposed at the through hole. As a result, the optical element can beleft intact without being influenced when the light transmissive memberis disposed at the through hole.

A method for manufacturing an optical device in accordance with thepresent invention comprises the steps of mounting an optical element ona substrate in which a through hole is formed in a manner that anoptical section thereof is placed to face the through hole, providinglight transmissive under-fill material between the substrate and theoptical element; and disposing a lens on the substrate in a manner tocover the through hole. Since the lens covers the through hole, a coverglass is not required, and the optical device can be made thinner,smaller and lighter.

In the method for manufacturing an optical device, a spacer may beprovided between the substrate and the lens. As a result, the positionof the lens can be adjusted according to a focal distance of the lens.

In the method for manufacturing an optical device, the lens may beprovided after the under-fill material is provided. As a result, sincethe under-fill material is provided in a state in which the through holeis opened, air can be removed and generation of bubbles can beprevented.

In the method for manufacturing an optical device, the under-fillmaterial may be provided after the lens is provided. As a result, theunder-fill material can be prevented from flowing out from the throughhole.

In the method for manufacturing an optical device, the lens may bemounted on the substrate after the optical element is mounted on thesubstrate. As a result, the lens can be left intact without beinginfluenced when an optical element is mounted.

In the method for manufacturing an optical device, the optical elementmay be mounted on the substrate after the lens is mounted on thesubstrate. As a result, the optical element can be left intact withoutbeing influenced when a lens is mounted on the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an optical device in accordance with a first embodiment ofthe present invention.

FIG. 2 shows an optical device in accordance with a second embodiment ofthe present invention.

FIG. 3 shows an optical device in accordance with a third embodiment ofthe present invention.

FIG. 4 shows a modified example of the third embodiment of the presentinvention.

FIG. 5 shows an optical device in accordance with a fourth embodiment ofthe present invention.

FIG. 6 shows an electronic apparatus having an optical device in whichthe present invention is applied.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention are described below withreference to the accompanying drawings.

FIG. 1 is an illustration showing an optical device in accordance with afirst embodiment of the present invention. The optical device includesat least one (one or multiple) optical element 10. The optical deviceincludes the packaged optical element 10. The optical element 10 has anoptical section 12. The optical element 10 may be a light receivingelement or a light emitting element. When the optical element 10 is alight emitting element, the optical section 12 is a light emittingsection. When the optical element 10 is a light receiving element, theoptical section 12 is a light receiving section.

In accordance with the present embodiment, the optical element 10 is animaging element (image sensor). When it is a two-dimensional imagesensor, the optical section 12 corresponds to a plurality of lightreceiving sections (for example, photo diodes) that compose a pluralityof pixels. In the case of a CCD (charge coupled device) type imagingelement, a transfer section not shown in the figure is provided totransfer charge from each light receiving section at each pixel at ahigh speed. In accordance with an embodiment different from the presentembodiment, a surface light emitting element, in particular, a surfacelight emitting laser may be provided as a modified example of theoptical element 10. The surface light emitting element such as a surfacelight emitting laser emits light in a direction perpendicular to thesubstrate that composes the element.

The optical element 10 may have at least one bump (a plurality of bumpsin the present embodiment) 14 in order to provide electrical connectionbetween the optical element 10 and the exterior. For example, the bumps14 for providing electrical connection with the exterior may be providedon a surface in which the optical section 12 is formed. The bumps 14 areprovided at positions where they can have electrical connection withother members. For example, the bumps 14 may be provided at locationsthat avoid a hole 24 in a substrate 20. The bumps 14 may preferablyprotrude compared to the optical section 12.

The optical device includes the substrate 20. The substrate 20 may havea low light transmissivity (or a light shielding characteristic). As thesubstrate 20, a silicon substrate or a glass epoxy substrate may beused. Alternatively, a flexible substrate or a film that is composedfrom polyimide resin may be used, or a multiple-layered substrate or abuild-up substrate may be used. Through holes 24 are formed in thesubstrate 20. The through holes 24 are formed in the same number as thenumber of the optical sections 12. The through hole 24 is formed in asize that encircles the optical section 12.

A wiring pattern 22 is formed on the substrate 20. The wiring pattern 22may be formed with a land as a region that is bonded to the opticalelement 10. The wiring pattern 22 may preferably be formed in a mannerto avoid the through hole 24 in the substrate 20. Also, the wiringpattern 22 may preferably be covered by another member (for example, aresist not shown in the figure) as long as it does not preventelectrical connection. The wiring pattern 22 shown in FIG. 1 is formedon only one surface of the substrate 20. However, wiring patterns 22 canbe formed on both surfaces of the substrate 20, and electricallyconnected to one anther through a through hole (not shown in thefigure).

In accordance with the present embodiment, the optical element 10 ismounted on the substrate 20 such that a face-down structure is formed.The bump 14 of the optical element 10 and the wiring pattern 22 areconnected to one another. If required, the optical element 10 and thewiring pattern 22 may be electrically connected by a wire not shown inthe figure. The optical element 10 is mounted in a manner that itsoptical section 12 coincides with the through hole 24. In other words,the optical element 10 is mounted on the substrate 20 with its opticalsection 12 being disposed to face the through hole 24.

The optical device includes a light transmissive member 30. The lighttransmissive member 30 may have a higher light transmissivity than thatof the substrate 20, or may be transparent. The light transmissivemember 30 may be composed, for example, from glass or resin (plastics).The light transmissive member 30 may be a substrate or may be in a blockshape. The light transmissive member 30 is disposed in the through hole24 in the substrate 20. More specifically, the light transmissive member30 may be pressure-inserted in the through hole 24, or may be disposedtherein with a small clearance provided between them. Since the lighttransmissive member 30 is disposed in the through hole 24, the opticaldevice can be made thinner, smaller and lighter.

When the thickness of the light transmissive member 30 is greater thanthe thickness of the substrate 20, it can be readily placed in thethrough hole 24. Also, the light transmissive member 30 may be providedin a manner that it does not protrude from a surface opposite to thesurface of the substrate 20 on which the optical element 10 is mounted.In the example shown in FIG. 1, the surface of the substrate 20 is flushwith the surface of the light transmissive member 30. By doing so, anincrease in the thickness by the light transmissive member 30 can beavoided.

A spacer 32 may be provided between the light transmissive member 30 andthe optical element 10. By providing the spacer 32, the space betweenthe light transmissive member 30 and the optical element 10 can beregulated, and the light transmissive member 30 is prevented fromcontacting the optical section 12. The spacer 32 may have a lightshielding characteristic. Also, the spacer 32 may be provided in amanner to encircle the optical section 12. When the spacer 32 and thesubstrate 20 has a light shielding characteristic, and the spacer 32encircles the optical section 12, light can be prevented from enteringthe optical section 12 through a space between the optical element 10and the substrate 20. In other words, light enters the optical section12 only through the light transmissive member 30.

Under-fill material 34 is provided between the light transmissive member30 and the optical element 10. The under-fill material 34 may be, forexample, resin, and may be adhesive. The under-fill material 34 may havelight transmissivity, and may preferably be transparent. In particular,the under-fill material 34 may preferably cover the optical section 12.By this, water content can be prevented from penetrating into theoptical section 12 (or the surface where the optical section 12 in theoptical element is formed). The under-fill material 34 is also providedbetween the substrate 20 and the optical element 10. Also, theunder-fill material 34 forms a fillet. The under-fill material 34alleviates stresses caused by a difference in the thermal expansioncoefficient between the optical element 10 and the substrate 20.

As shown in FIG. 1, external terminals 36 may be provided. The externalterminals 36 are for example solder balls, and are provided on thewiring pattern 22. Alternatively, a part of the wiring pattern 22 may beformed into a connector, or a connector may be mounted on the wiringpattern 22.

The optical device in accordance with the present embodiment isstructured in a manner described above, and a method for manufacturingthe same is described below. In accordance with the method formanufacturing an optical device, an optical element 10 is mounted on asubstrate 20 in which a through hole 24 is formed with its opticalsection 12 being placed to face the through hole 24. Also, a lighttransmissive under-fill material 34 is provided between the substrate 20and the optical element 10. Also, a light transmissive member 30 isdisposed in the through hole 24. For example, the following embodimentscan be provided.

The optical element 10 is mounted on the substrate 20 and the under-fillmaterial 34 is provided, and thereafter the light transmissive member 30is disposed in the through hole 24. In this case, the light transmissivemember 30 may preferably be smaller than the through hole 24 so that itcan be disposed in the through hole 24 with a clearance between them.Then, the light transmissive member 30 is adhered to the under-fillmaterial 34 in the through hole 24. By this method, the under-fillmaterial 34 is provided in a state in which the through hole 24 is open,such that air-removal is feasible and generation of bubbles can beavoided. Also, since the optical element 10 is mounted on the substrate20 and then the light transmissive member 30 is provided, the lighttransmissive member 30 is not affected by the incident of mounting theoptical element 10.

(2) After the optical element 10 is mounted on the substrate 20 and thelight transmissive member 30 is disposed in the through hole 24, thenthe under-fill material 34 is provided. In this case, the spacer 32 maypreferably be provided on the optical element 10 to support the lighttransmissive member 30. By this method, the under-fill material 34 isprovided after the through hole 24 is closed by the light transmissivemember 30. As a result, the under-fill material 34 can be prevented fromflowing out from the through hole 24. Also, since the optical element 10is mounted on substrate 20 and then the light transmissive member 30 isprovided, the light transmissive member 30 is not affected by theincident of mounting the optical element 10.

(3) After the light transmissive member 30 is disposed in the throughhole 24 and the optical element 10 is mounted on the substrate 20, thenthe under-fill material 34 is provided. In this case, the lighttransmissive member 30 may preferably be fixed within the through hole24. In accordance with this method, the through hole 24 is closed by thelight transmissive member 30, and then the under-fill material 34 isprovided. As a result, the under-fill material 34 can be prevented fromflowing out from the through hole 24. Also, since the light transmissivemember 30 is disposed in the through hole 24, and then the opticalelement 10 is mounted on substrate 20, the optical element 10 is notaffected by the incident of disposing the light transmissive member 30in the through hole 24.

(4) After the light transmissive member 30 is disposed in the throughhole 24 and the under-fill material 34 is provided, then the opticalelement 10 is mounted on the substrate 20. In this case, the under-fillmaterial 34 is provided on at least one of the light transmissive member30 disposed in the through hole 24 and the optical element 10. Also, thelight transmissive member 30 may preferably be fixed within the throughhole 24. In accordance with this method, the through hole 24 is closedby the light transmissive member 30, and then the under-fill material 34is provided. As a result, the under-fill material 34 can be preventedfrom flowing out from the through hole 24. Also, since the lighttransmissive member 30 is disposed in the through hole 24, and then theoptical element 10 is mounted on substrate 20, the optical element 10 isnot affected by the incident of disposing the light transmissive member30 in the through hole 24.

By the methods described above, thinner, smaller and lighter opticaldevicees can be manufactured. The present invention is not limited tothe embodiments described above. Other embodiments are described below.

FIG. 2 shows an optical device in accordance with a second embodiment ofthe present invention. In this embodiment, the light transmissive member40 is in the shape of a lens. External terminals are not provided in theexample shown in FIG. 2, but may be provided therein. Structures andmanufacturing steps other than the above correspond to those describedabove in the first embodiment. In accordance with the presentembodiment, light that enters the light transmissive member 40 can beconverged. A spacer 32 may preferably be provided to correctly positionthe light transmissive member 40. Also, light may preferably beconverged inside the spacer 32. The present embodiment can also achievethe effects described in connection with the first embodiment.

FIG. 3 shows an optical device in accordance with a third embodiment ofthe present invention. The optical device in accordance with the presentembodiment has a lens 50 that serves as a light transmissive member, andtherefore it can converge light. Also, the lens 50 is larger than thethrough hole 24 in the substrate 20. The lens 50 is mounted on thesubstrate 20 in a manner to cover the through hole 24. The under-fillmaterial 34 is provided between the substrate 20 and the optical element10 and between the lens 50 and the optical element 10. It is noted thatthe under-fill material 34 shown in FIG. 3 may be used to adhere thelens 50 and the substrate 20 to one anther, or another adhesive may beused. In the present embodiment, although neither external terminal norspacer is provided, they can be provided. Structures and manufacturingsteps other than the above correspond to the contents described abovewith respect to the first embodiment. In accordance with the presentembodiment, since the through hole 24 is closed by the lens 50, a coverglass is not required, such that the optical device can be made thinner,smaller and lighter.

In the method for manufacturing the optical device in accordance withthe present embodiment, the lens 50 is provided on the substrate 20,instead of a light transmissive member 30 disposed in a through hole 24as provided in the first embodiment. The contents described withreference to the first embodiment are applicable to the detailstherefor.

In a modified example of the present embodiment, a spacer 52 may beprovided between the lens 50 and the substrate 20, as shown in FIG. 4.The lens 50 can be located at a position according to its focaldistance.

FIG. 5 shows an optical device in accordance with a fourth embodiment ofthe present invention. The optical device of the present embodiment isprovided with at least one (one or plural) electronic part 70 inaddition to an optical element 10 mounted on a substrate 60. Theelectronic part 70 may be any one of a passive element (resistor,capacitor, inductor), an active element (semiconductor element,integrated circuit), a connection part (switch, wiring plate), afunctional part (filter, oscillator, delay line), and a conversion part(sensor). The electronic part 70 may be a driver IC for driving theoptical element 10. The electronic part 70 shown in FIG. 5 is aface-mounting type part, but may be a lead-mounting part. The mountingstructure of the electronic part 70 is not particularly limited, and itcan be either a face-down structure or a face-up structure. Wiringpatterns 62 electrically connect the optical element 10 and theelectronic part 70.

As shown in FIG. 5, the substrate 60 may be curved. In this case, aflexible substrate may be used as the substrate 60. Also, the opticalelement 10 and the electronic part 70 may be adhered to one another. Forexample, a surface of the optical element 10 opposite to its surface tobe mounted on the substrate 60 may be adhered to a surface of theelectronic part 70 opposite to its surface to be mounted on thesubstrate 60. Alternatively, the substrate 60 may be bent, and portionsof its opposing surfaces may be adhered to one another to maintain thesubstrate 60 in a bent state. Adhesive may be used for the adhesion.

The contents described above with respect to the first through thirdembodiments are applicable to the present embodiment. The optical devicein accordance with the present embodiment can also be made thinner,smaller and lighter.

FIG. 6 shows a digital camera 100 as one example of electronic apparatushaving an optical device in which the present invention is implemented.

The entire disclosure of Japanese Patent Application No. 2000-395112(P)filed Dec. 26, 2000 is incorporated by reference herein.

1. A method of manufacturing an optical device that includes a substratehaving a through-hole, an upper surface and a lower surface, and anoptical element having an optical section placed to face the throughhole, the method comprising: mounting the optical element to the lowersurface of the substrate; disposing a spacer on a portion of the uppersurface of the substrate; disposing a light transmissive under-fillmaterial between the lower surface of the substrate and the opticalelement, at the through-hole and on the spacer; and disposing a lighttransmissive member on the light transmissive under-fill material. 2.The method of manufacturing the optical device according to claim 1, thedisposing of the light transmissive member on the light transmissiveunder-fill material including disposing the light transmissive member ina lens shape.
 3. The method of manufacturing the optical deviceaccording to claim 1, the disposing of the light transmissive member onthe light transmissive under-fill material including disposing the lighttransmissive member to cover the through-hole.
 4. The method ofmanufacturing the optical device according to claim 1, the spacer beingdisposed to position the light transmissive member such that a lightthat passes through the light transmissive member is converged insidethe spacer.